/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.heron.api.windowing;

import org.apache.heron.api.tuple.Tuple;

/**
 * A {@link TimestampExtractor} that extracts timestamp from a specific field in the tuple.
 */
public final class TupleFieldTimestampExtractor implements TimestampExtractor {
  private static final long serialVersionUID = 6302970084936569305L;
  private final String fieldName;

  private TupleFieldTimestampExtractor(String fieldName) {
    this.fieldName = fieldName;
  }

  @Override
  public long extractTimestamp(Tuple tuple) {
    return tuple.getLongByField(fieldName);
  }

  public static TupleFieldTimestampExtractor of(String fieldName) {
    return new TupleFieldTimestampExtractor(fieldName);
  }

  @Override
  public String toString() {
    return "TupleFieldTimestampExtractor{" + "fieldName='" + fieldName + '\'' + '}';
  }
}
